Purification of burner-gases.



J. B. F. HERRBSHOFF.

PURIFIOATION 0F BURNER GASES.

APPLICATION FILED FEB. 10, 1900.

INVENTOR ATTORNEYS UNITED STATES PATENT OFFICE.

JOHN BROWN FRANCIS HERBESHOFF, OF NEW YORK, N. Y., ASSIGNOB TO GENERAL GHEKICAL COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PURIFICATION OF BURNER-GASES.

Specification of Letter: intent.

Patented Nov. 16, 1909.

To allwlwm it may concern:

Be it known that I, JOHN Bnowu FRANCIS Hnnusuorr, a citizen of the United States,

and resident of the boron h of Manhattan, cit county, and State 0 New York, have in ented certain new and useful Improven" nts in the Purification of Burner-Gases, o which the following is a specification.

My invention relates to the purification of burner gases such as are produced from sulfid ores and other, materials used in the manufacture of sulfuric acid, and especially to a purification which will render such gases suitable for the manufacture of sulfuric anhydrid and of sulfuric acid by the so-called contact process in which the sulfur dioxid contained in such gases is caused to combine with oxygen by the catalytic action of platinum or equivalent material.

The continued efficiency of the contact process for the n-mnufacture of sulfuric :mhydrid depends among other things upon the pro )er purification of the burner gases:

before t icy are allowed to enter the contact chamber. It has been found that the purification precediu the catalytic process should be so conducted as to remove certain. detrimental im urities amon which I will name particular y sulfuric acid (present in the form of mist), sulfur, arsenic, antimony,

selenium, tellurium, and hydrofluoric acid. The failure to eliminate these bodies before the catalytic reaction occurs will materially reduce the efficiency of the contact process, such bodies acting, as it were, as a poison by diminishing or destroying the catalytic activity of the platinum. On the other hand, nitrogen, which is a constituent of the burner as mixture and which does not. enter into i no reaction, may be carried along with the purified gases without any dctrluu'utal cll'cctmi the contact [)lfllt'ss.

y present invention rclalcs to an iu|- proved process for purifying gases containmg 30, and mrlicu arly burner gases. which process invo res the removal from the said gases, of arsenic, sulfur, sulfuric acid mist, and other dolrinwutal impurilics which o:- our in burner gases, leaving as the useful product of the operation a pure burner gas, that is. n gin-z consisting of sulfur dioxid, oxygen, and inert gases. uhielly nitrogen, in

substantially the same amount which was contained in the original impure burner as; this purified burner gas can then prooee on its way to further treatment, as by catalytic conversion into S0,.

W'hilc the exact manner of carrying out my invention will vary more or less according to the constitution of the impure burner and articularly awarding to the nature of tie detrimental impurities contained therein, certain general princi ales of operation such as ointed out in t 1e appended claims, will e observed.

I have described hereinafter a particular embodiment of my invention but it will be understood that variations, as long as they remain within the scope of the appended claims, will constitute no departure from the nature of my invention.

Reference is to be had to the accompanying drawing. which is a diagralnn'iatic view, partly in section, of a plant such as may be employed in carrying out my present inventlon.

A designates furnaces where the ore is roasted. The furnace ses or burner gases pass through conduits fi into a dust chamber (3 of a cross section considerably greater than that of the conduits B, so that the gases will move more slowly in the dust chamber C, allowing the suspended solid particles to set tle out thcrcin. From this chamber C the gases pass through another conduit D to the cooling and scrubbing tower E, the path of the gases to said tower being such that their temperature is reduced to about 650 1'. at their entrance into the tower. The gases pass upward in the tower E which contains a filling F of quartz stones or other suitable material, and n largo quantity of a purifying licplid, preferably cool weak sulfuric acid, or instance of 40" H6.) trickles downward over the filling. This treatmentwith finely divided cool weak sulfuric acid has a double ctl'ccl, one of which is to furlhcl' cool the gases, and the ullu't' to scrub them. The chief ronslilucllls of the lllllllt'l gases arr S0,, 0, and N. 'l'ho an-s also contain various liquid and Hlllltblllllilltlllifi, and the settling and arrnhhin" systcmluls to he so designed that it will rl inunulv with practicalv cmuplnll'unss all of the solid impuriluss. The

sulfur, like solid (sublimed) arsenic, has a very detrimental influence on the activity of the contact substance.

The liquid impurities such as dissolved arsenic occur in the sulfuric acid, winch 1s alwa 5 formed when roasting sulfide and whic in the gases is present in the nature of a mist, and it has been found that if such sulfuric acid is carried along through the remainder of the purifging process it sericusly interferes with t e efliciency of said recess, requiring a very thorough and more engthy purification than is necessary otherwise. Furthermore, the resence of sulfuric acid in the contact chain ers interferes with the efiiciency of the catalytic action. The arsenic, (as well as HFl and Se) is also dungerous to the catalytic activity of the platinum, and must be removed before the gases enter the contact chamber, or such arsenic will soon diminish the activity of the contact mass to a very material extent.

The preliminary cooling of the gases on their way to the cooling and scrubbing tower E is of assistance, as it enables the gases to be purified more readily when they come in contact with the weak acid trickling down in said tower. In the scrubbin tower the nirificatiou of the burner gases rom S, H, 0,, As and other detrimental impurities is carried on very elficiently owing to the large surface and to the intimate contact. of the gases with the li uid which is brou ht about by the fine division of the weak acit If desired, and I consider this preferable, the gases mabe passed in succession through several scru hing towers. Thus, the drawing shows two additional scrubbing towers E E, with fillings F, F of the same character as hereinbefore described. Pipes G, G connect the upper portion of one tower with the lower portion of the next and serve to convey the gases. The spra heads for so pllying the weak acid are in icated at H, l

and the outlets for the weak acid at J, J J-'. I prefer to use the same body of acid over and over a ain, and for this purpose, the acid from t e outlet J passes into a cooler K and then through a settlin box L having bathe-hoards or other means or cans ing impurities to be thrown down. A pump M returns the cooled and purified acid throu h a pipe N to the s ra v head H. The acid iron] the towers E It is preferably led to the same cooler K". then to the set 'tliug box L, and finally brought back to the it can absorb at the temperature to which it is heated in the scrubbing towers. The cool acid does indeed absorb an additional amount of S0,, but as the acid becomes heated, this additional amount is liberated in the scrubbing towers and passes alou with the gases. The towers E, E E, as we I as the coolers K, K, and settling boxes L, L, should he closed to the atmosphere so as to revent the escape of any SO which may be liberated in any one of t iese apparatus.

, The purification in the scrubbin towers should e so thorough that the soli impurities will be practically eliminated and will not percepti ly affect the operation of the remainder of the a aratus. The gases thus deprived of the so id impurities, of a portion of the liqluid mist, and of gaseous iiupurities as wel pass through the conduit to the filter 0, preferably filled with fine, dry sand, coke or other medium, therefore it is very important that no solid matter should be rmitted to enter the filter. The filter is 0 eat area and depth. In this filter, the acid mist containing As, and most of the moisture, are removed from the gases and the purification is completed. Finally, the gases are dried in a drving tower P by contact with mncentratcd sulfuric acid tricklin down in the usual way. A blower Q or oter suitable device is em loyed for causing the ses to follow the put I set forth. The uriliefi ascs pass on to the contact chain r or 0t ier apparatus.

The recess herembcfore described removes t e H 30 S, HFl, As and other detrimental impurities from the burner gases but leaves the contents of S0,. and of other constituents, that is, chiefly O and N, )ractically unaltered. Those constituents there fore, S0, and O, which are the active const-ituents m the contact process, and N, which is inert, are preserved in their practical entirety, while the detrimental impurities are removed.

The gases, at the end of the purifying process herem described, should satisfy an optical test. showing their practically ahsw lute freedom from solid or liquid matter.

I claim as my invent ion:

1. The herein described process of purifying gases containing S0,, which consists in bringin the gases into contact. with a "llnntely distributed body of weal: acid containing abmrbcd SO. and cxposin them to the action of such acid until the solid impurities have been practically eliminated, and then removing non-solid impurities by fill-ration.

2. The herein described process of purifying gases containing S0,, which consists in briu in the gases into contact; with a minute v distributed body of weak acid mull-nining absorlasd bill, and cxposiu r them to the action of such acid until the so id impurities have boen practically eliminated, removin my name, in the presence of twosubscribing such acid from contact with the gases coo wltnesses. ing and purifying it and returnmg 11; into contact with the gases, u nd thereupon re- JOHN BROWN FRANCIS ussnssuow, 5 moving the liquid lmpuritles from the gases VIUIGSSGSZ by filtratlon. Joux Lum,

In testimony whereof, I have hereunto set JOHN A. Knnwxnncx. 

